Encryption is a big deal -- it's used to keep on-line transactions secure, as well as securing your sensitive data in databases maintained by banks etc. It can also be used to keep intruders out of your private conversations & files, & increasingly since the Snowdon docs release, it's used to keep on-line traffic, e.g. between Google's server locations, private as well.
In a nutshell, the Snowdon docs showed some of the ways government agencies were capturing & saving what was thought to be private data, conversations etc. In response, companies like Google, Microsoft, Apple etc. beefed up their use of encryption to stop some of that activity. Such steps *might* have also been necessary to comply with EU regs regarding protection of an individual's private data. Those gov agencies involved would like all of their prior capabilities back.
In order to get their prior access back, & to get additional access to files & data, several US agencies are pushing for laws that would give the gov special keys to unlock any & all encryption. Since encryption involves far more than keeping conversations between criminals safe, several notable cryptography experts have published a paper detailing why this could be such a very bad idea.
"Computer Science and Artificial Intelligence Laboratory Technical Report"
"Keys Under Doormats: Mandating insecurity by requiring government access to all data and communications Harold Abelson, Ross Anderson, Steven M. Bellovin, Josh Benaloh, Matthew Blaze, Whitfield Diffie, John Gilmore, Matthew Green, Peter G. Neumann, Susan Landau, Ronald L. Rivest, Jeffrey I. Schiller, Bruce Schneier, Michael Specter, and Daniel J. Weitzner"
Link to PDF
http://dspace.mit.edu/bitstream/handle/1721.1/97690/MIT-CSAIL-TR-2015-026.pdf?sequence=6